Specific embodiment
The characteristics of in order to more fully hereinafter understand the embodiment of the present disclosure and technology contents, with reference to the accompanying drawing to this public affairs
The realization for opening embodiment is described in detail, appended attached drawing purposes of discussion only for reference, is not used to limit the embodiment of the present disclosure.
In technical description below, for convenience of explanation for the sake of, disclosed embodiment is fully understood with providing by multiple details.
However, one or more embodiments still can be implemented in the case where without these details.It in other cases, is simplification
Attached drawing, well known construction and device can simplify displaying.
Fig. 1 is the flow diagram for the control method for air-conditioner defrosting that the embodiment of the present disclosure provides.
A kind of control method for air-conditioner defrosting is provided in the embodiment of the present disclosure, as shown in Figure 1, including following step
It is rapid:
S101: in the case where air-conditioning is defrosted, control goes out liquid to the refrigerant for the outdoor heat exchanger for flowing through air-conditioning
The refrigerant of pipeline heats.
In embodiment, when frosting problem occurs in the outdoor heat exchanger of air-conditioner outdoor unit, outdoor environment is mostly in temperature
Lower, the biggish bad working environments of humidity, user is usually that air-conditioning is set as heating mode operation at this time, to utilize air-conditioning to room
Interior environment carries out heating heating.Therefore the control method for air-conditioner defrosting that the embodiment of the present disclosure provides is in air-conditioning to heat
The control flow enabled when mode operation.
Optionally, judge by way of compared with numerical value between outdoor environment temperature and frost point temperature air-conditioning whether need into
Row defrosting.When outdoor environment temperature is lower than frost point temperature, then it is assumed that air-conditioning defrosts;When outdoor environment temperature is higher than
When frost point temperature, then it is assumed that air-conditioning is without defrosting.
The defrosting operation of air-conditioning includes that control carries out the refrigerant on the refrigerant outlet tube road for the outdoor heat exchanger for flowing through air-conditioning
Heating can be further improved the refrigerant temperature for flowing into indoor heat exchanger by the heating to the refrigerant for flowing through refrigerant outlet tube road
Degree, so as to enhance actual defrosting effect.
Optionally, it is provided with a heating device at the refrigerant outlet tube road of outdoor heat exchanger of air conditioner, which is set
It is set to and controllably the refrigerant for flowing through refrigerant outlet tube road is heated.In the case where air-conditioning needs to defrost, can control out
Open heating device;And in the case where air-conditioning is without heating, then keep the closed state of heating device.
In one embodiment, heating device is electromagnetic heater, and electromagnetic heater utilizes electromagnetic induction heating
Principle heats refrigerant pipeline, and then the refrigerant for flowing through refrigerant pipeline is conducted heat to using refrigerant pipeline, cold to reach heating
The purpose of matchmaker.
Here, the corresponding refrigerant pipe section heated of electromagnetic heater is the pipeline section of the metal materials such as copper or irony,
Electromagnetic heater is mainly made of induction coil and power supply module, and induction coil is wound in above-mentioned refrigerant pipeline here
Section, power supply module can provide alternating current for induction coil;When induction coil is powered, the alternating current of induction coil is flowed through
The alternating magnetic field for passing through refrigerant pipe section is generated, which can make refrigerant inner tube segment generate vortex, so as to rely on
The energy of these vortex plays the role of heat temperature raising.
It is filled it should be understood that the type for the heating device that the application is used to heat refrigerant is not limited to above-mentioned electromagnetic heating
It sets, the other types of heating device that can be used in directly or indirectly heating refrigerant can also be using the application's in the related technology
Technical solution, and cover within the scope of protection of this application.
S102: the outdoor coil temperature, heating times and heating duration of outdoor heat exchanger are obtained.
Optionally, the coil pipe position of the outdoor heat exchanger of air-conditioner outdoor unit is provided with one first temperature sensor, this
One temperature sensor can be used for detecting the real time temperature of coil pipe position.Therefore, acquired outdoor coil pipe used temperature in step s 102
Degree can be the real time temperature by coil pipe position detected by the first temperature sensor.
The temperature change of the coil pipe position of outdoor heat exchanger can intuitively reflect in external outdoor environment temperature and interior
The temperature variations of the refrigerant pipeline of outdoor heat exchanger, are in addition typically also outdoor heat exchange under the refrigerant temperature joint effect in portion
Device is easy to appear the pipeline position of frosting problem.Therefore the outdoor coil temperature got, which can be used as, measures air-conditioning inside and outside pair
The reference factor that the frosting that outdoor heat exchanger generates jointly influences.
Heating times are the refrigerant heating in preset time to the refrigerant outlet tube road for the outdoor heat exchanger for flowing through air-conditioning
Heating times;When the heating that a length of last heats the refrigerant on the refrigerant outlet tube road for the outdoor heat exchanger for flowing through air-conditioning when heating
It is long.
The refrigerant on the refrigerant outlet tube road for the outdoor heat exchanger for flowing through air-conditioning is heated in control, improves inflow outdoor and changes
The temperature of the refrigerant of hot device is to utilize the frost of the refrigerant heat thawing outdoor heat exchanger after temperature raising.It is halfway in defrost
In the case of, there can be the case where frequently heating defrost and extension of single heating defrost time.Therefore when heating times and heating
Whether the long heating defrosting operation that can be used as defrosts thorough reference factor.
S103: in the case where outdoor coil temperature, heating times and defrosting time meet the first preset condition, control is empty
It transfers in into reverse cycle defrosting mode.
Reverse cycle defrosting mode includes that the refrigerant flow direction of control air-conditioning is switched to the flow direction opposite with heating mode;In this kind
Under model process, the high temperature refrigerant of compressor discharge is first to flow through outdoor heat exchanger, so as to utilize the heat of high temperature refrigerant
Realize the defrosting operation to outdoor heat exchanger.
Optionally, the first preset condition are as follows:
T1≤T01, t1≥t01, T0-T1<ΔT0, N1≥N01, and t2≥t02
Wherein, T1For the outdoor coil temperature of outdoor heat exchanger, T01For the first preset temperature, T0It is first when being switched on for air-conditioning
Beginning outdoor coil temperature, Δ T0For fiducial temperature threshold value, t1For T1≤T01Duration, t01For the first preset duration, N1It is right
Flow through the heating times of the refrigerant heating on the refrigerant outlet tube road of outdoor heat exchanger, N01To preset heating times, t2For N1It is secondary
To the heating duration of the refrigerant heating on the refrigerant outlet tube road for flowing through outdoor heat exchanger, t02For the second preset duration.
Optionally, the value range of the first preset temperature is [3 DEG C, 6 DEG C] (DEG C: degree Celsius), for example, 3 DEG C, 4 DEG C, 5 DEG C,
6℃;The value range of fiducial temperature threshold value is [3 DEG C, 6 DEG C], for example, 3 DEG C, 4 DEG C, 5 DEG C, 6 DEG C;The value of first preset duration
Range is [50s, 70s] (s: second), for example, 50s, 60s, 70s;The value range of second preset duration is [2min, 4min]
(min: minute), for example, 2min, 3min, 4min;The value range of default heating times is [2 times, 4 times], for example, 2 times, 3
It is secondary, 4 times.
For example, 5 degree were less than at outdoor coil temperature continuous 60 seconds, outdoor coil temperature and initial outdoor coil temperature
Temperature gap is 4 degree, and heating times are more than that 3 times and the 3rd time humidification durations are greater than 3 minutes, then controls air-conditioning and remove into inverse circulation
White mode.
Optionally, it controls and the refrigerant on the refrigerant outlet tube road for flowing through outdoor heat exchanger is heated, comprising:
Go out the temperature gap of liquid temperature according to the refrigerant that the initial refrigerant of outdoor heat exchanger goes out liquid temperature and outdoor heat exchanger
Determine the heating parameters of heating;
Control is heated according to refrigerant of the heating parameters to the refrigerant outlet tube road for flowing through outdoor heat exchanger;
Wherein, heating parameters include target heating rate, target heating duration or target heating interruption duration.
Optionally, the outdoor heat exchanger of air-conditioner outdoor unit is provided with a second temperature sensor, second temperature sensing
Device can be used for detecting the real time temperature of the refrigerant on the refrigerant outlet tube road for flowing through outdoor heat exchanger.Therefore, acquired outdoor is changed
The refrigerant of hot device, which goes out liquid temperature, can be real time temperature by refrigerant detected by second temperature sensor.Here, refrigerant
When outlet tube road is run for air-conditioning with heating mode refrigerant outflow outdoor heat exchanger via pipeline.
In the case where air-conditioning is defrosted, control adds the refrigerant on the refrigerant outlet tube road for flowing through outdoor heat exchanger
Heat, it is known that it is that the refrigerant under outdoor heat exchanger frosting situation goes out liquid temperature that the initial refrigerant of outdoor heat exchanger, which goes out liquid temperature,.With
The progress of heating defrosting operation, the refrigerant of outdoor heat exchanger go out liquid temperature and gradually rise.Therefore, the initial refrigerant of outdoor heat exchanger
The temperature gap that liquid temperature and refrigerant go out liquid temperature out can reflect the defrosting situation of air-conditioning.Temperature gap is smaller, then illustrates sky
It adjusts the frosting degree of outdoor heat exchanger more serious, needs to improve the rate of heat addition at this time, increase heating duration, shorten heating interruption
Duration accelerates defrost;Temperature gap is larger, then illustrates the frosting lesser extent of outdoor heat exchanger of air conditioner, can suitably reduce and add
Hot rate shortens heating duration, increases heating interruption duration, plays the role of energy-efficient.Therefore, it can be determined according to temperature gap
The heating parameters of heating.It is heated according to corresponding heating parameters, in the case where ensuring that air-conditioning normally defrosts, is reduced to the greatest extent
The operation power consumption of heating devices heat refrigerant, plays the role of energy-efficient.
Optionally, target heating rate is determined according to temperature gap, comprising:
According to temperature gap, the corresponding rate of heat addition is obtained from rate of heat addition incidence relation and using the rate of heat addition as mesh
Mark the rate of heat addition.
It include the corresponding relationship of one or more temperature gaps and the rate of heat addition in rate of heat addition incidence relation.For example, table 1
Show corresponding relationship (wherein, the Δ T=T of a kind of optional temperature gap and the rate of heat addition2-TInitially, Δ T is outdoor heat exchanger
Initial refrigerant go out liquid temperature and refrigerant goes out the temperature gap of liquid temperature, TInitiallyGo out liquid temperature for the initial refrigerant of outdoor heat exchanger
Degree):
Table 1: rate of heat addition incidence relation
Temperature gap (unit: DEG C) |
The rate of heat addition (unit: DEG C/min) |
a1<ΔT≤a2 |
V1 |
a2<ΔT≤a3 |
V2 |
a3<ΔT |
V3 |
In rate of heat addition incidence relation, the rate of heat addition is negatively correlated with temperature gap.That is, temperature gap is bigger, heating speed
Rate is smaller;Temperature gap is smaller, and the rate of heat addition is bigger.
Optionally, determine that target heats duration according to temperature gap, comprising:
According to temperature gap, corresponding heating duration is obtained from heating duration incidence relation and will heat duration as mesh
Mark heating duration.
Heat includes one or more temperature gaps and the corresponding relationship for heating duration in duration incidence relation.For example, table 2
Show the corresponding relationship of a kind of optional temperature gap and heating duration:
Table 2: heating duration incidence relation
Temperature gap (unit: DEG C) |
It heats duration (unit: min) |
a1<ΔT≤a2 |
t11 |
a2<ΔT≤a3 |
t12 |
a3<ΔT |
t13 |
It heats in duration incidence relation, heats duration and temperature gap is negatively correlated.That is, temperature gap is bigger, when heating
Length is smaller;Temperature gap is smaller, and heating duration is bigger.
Optionally, target heating interruption duration is determined according to temperature gap, comprising:
According to temperature gap, between obtaining corresponding heating interruption duration in heating interruption duration incidence relation and will heat
Disconnected duration heats interruption duration as target.
It include the corresponding relationship of one or more temperature gaps and heating interruption duration in heating interruption duration incidence relation.
For example, table 3 shows the corresponding relationship of a kind of optional temperature gap and heating interruption duration:
Table 3: heating interruption duration incidence relation
Temperature gap (unit: DEG C) |
Heating interruption duration (unit: min) |
a1<ΔT≤a2 |
t21 |
a2<ΔT≤a3 |
t22 |
a3<ΔT |
t23 |
In heating interruption duration incidence relation, heating interruption duration is positively correlated with temperature gap.That is, temperature gap is got over
Greatly, heating interruption duration is bigger;Temperature gap is smaller, and heating interruption duration is smaller.
In some embodiments, after controlling to the refrigerant heating on the refrigerant outlet tube road for flowing through outdoor heat exchanger, also
Include:
The refrigerant for obtaining outdoor heat exchanger goes out liquid temperature;
In the case where refrigerant goes out liquid temperature and meets the second preset condition, control stops to the outdoor heat exchanger for flowing through air-conditioning
Refrigerant inlet pipe and refrigerant outlet tube road refrigerant heating.
The temperature for flowing out the refrigerant of outdoor heat exchanger is to can reflect out the heat exchange effect of outdoor heat exchanger and outdoor environment
Rate, and heat exchanger effectiveness then will receive the influence of the frosting degree of outdoor heat exchanger;Here, air-conditioning frosting degree is lower, ice
In the case that frost thickness are relatively thin, influence of the frost to heat exchange is smaller, the heat that the refrigerant after flowing through outdoor heat exchanger is absorbed
It is more;And in the case where air-conditioning frosting degree is higher, frost thickness is thicker, frost is affected to heat exchange, flows through room
The heat that refrigerant after external heat exchanger is absorbed is less.Therefore the refrigerant that acquires, which goes out liquid temperature and can be used as, measures air-conditioning and changes
The reference factor of the frosting degree of hot device.
Optionally, the second preset condition are as follows:
T2≥T02, and t3≥t03
Wherein, T2Go out liquid temperature, T for the refrigerant of outdoor heat exchanger02For the second preset temperature, t3For T2≥T02It is lasting when
It is long, t03For third preset duration.
In second preset condition, the refrigerant of outdoor heat exchanger goes out liquid temperature greater than the second preset temperature and duration
Greater than third preset duration, the heating performance that can reflect out outdoor heat exchanger restores at least frost or frostless situation.It therefore, can be with
Stop heating the refrigerant on the refrigerant outlet tube road for the outdoor heat exchanger for flowing through air-conditioning, reduces the function of heating devices heat refrigerant
Consumption, reduces the cost of operation of air conditioner.
Fig. 2 is the flow diagram for the control method for air-conditioner defrosting that the embodiment of the present disclosure provides.
A kind of control method for air-conditioner defrosting is provided in the embodiment of the present disclosure, as shown in Fig. 2, including following step
It is rapid:
S201: judge whether air-conditioning defrosts.
S202: in the case where air-conditioning is defrosted, the initial refrigerant for obtaining outdoor heat exchanger goes out liquid temperature and room
The refrigerant of external heat exchanger goes out the temperature gap of liquid temperature.
S203: the heating parameters of heating are determined according to temperature gap.
S204: control is heated according to refrigerant of the heating parameters to the refrigerant outlet tube road for flowing through outdoor heat exchanger.
S205: the refrigerant for obtaining outdoor heat exchanger goes out liquid temperature.
S206: judge that refrigerant goes out whether liquid temperature meets the second preset condition.
S207: in the case where refrigerant goes out liquid temperature and meets the second preset condition, control stops to flowing through outdoor heat exchanger
Refrigerant outlet tube road refrigerant heating.
S208: the outdoor coil temperature, heating times and heating duration of outdoor heat exchanger are obtained.
S209: judge whether outdoor coil temperature, heating times and defrosting time meet the first preset condition.
S210: in the case where outdoor coil temperature, heating times and defrosting time meet the first preset condition, control is empty
It transfers in into reverse cycle defrosting mode.
In the present embodiment, when using the outdoor coil temperature of outdoor heat exchanger, the heating times of heating device and heating
These long parametric synthesis judge that air-conditioning enters the opportunity of reverse cycle defrosting mode, air-conditioning frosting and other air-conditioning is normally made
Control air-conditioning enters reverse cycle defrosting mode in the halfway situation of the lesser Defrost mode defrosting of heat affecting, improves empty to control
The control precision into reverse cycle defrosting mode is transferred in, the air-conditioning when outdoor heat exchanger needs to defrost is avoided to run reverse cycle defrosting
Mode and to the normal heating performance of air-conditioning constitute larger impact.
Fig. 3 is the structural schematic diagram for the control device for air-conditioner defrosting that the embodiment of the present disclosure provides.
The embodiment of the present disclosure provides a kind of control device for air-conditioner defrosting, and structure is as shown in Figure 3, comprising:
Processor (processor) 30 and memory (memory) 31 can also include communication interface
(Communication Interface) 32 and bus 33.Wherein, processor 30, communication interface 32, memory 31 can pass through
Bus 33 completes mutual communication.Communication interface 32 can be used for information transmission.Processor 30 can call in memory 31
Logical order, to execute the control method for air-conditioner defrosting of above-described embodiment.
In addition, the logical order in above-mentioned memory 31 can be realized and as only by way of SFU software functional unit
Vertical product when selling or using, can store in a computer readable storage medium.
Memory 31 is used as a kind of computer readable storage medium, can be used for storing software program, journey can be performed in computer
Sequence, such as the corresponding program instruction/module of the method in the embodiment of the present disclosure.Processor 30 is stored in memory 31 by operation
Program instruction/module be used for air-conditioning in realization above method embodiment thereby executing functional application and data processing
The control method of defrosting.
Memory 31 may include storing program area and storage data area, wherein storing program area can storage program area, extremely
Application program needed for a few function;Storage data area, which can be stored, uses created data etc. according to terminal device.This
Outside, memory 31 may include high-speed random access memory, can also include nonvolatile memory.
Fig. 4 is the structural schematic diagram for the air-conditioning that the embodiment of the present disclosure provides.
The embodiment of the present disclosure provides a kind of air-conditioning, as shown in Figure 4, comprising:
Refrigerant circulation circuit passes through refrigerant by outdoor heat exchanger 41, indoor heat exchanger 42, throttling set 43 and compressor 44
Piping connection is constituted;
Heating device 45 is set to the refrigerant outlet tube road of outdoor heat exchanger 41 in a heating mode, is configured as pair
The refrigerant for flowing through refrigerant outlet tube road is heated;
The above-mentioned control device 46 for air-conditioner defrosting, is electrically connected with heating device 45.
The air-conditioning that the embodiment of the present disclosure provides utilizes the heating time of the outdoor coil temperature, heating device of outdoor heat exchanger
Number and heating these parametric synthesis of duration judges that air-conditioning enters the opportunity of reverse cycle defrosting mode, improve to control air-conditioning into
The control precision for entering reverse cycle defrosting mode avoids the air-conditioning when outdoor heat exchanger needs to defrost from running reverse cycle defrosting mould
Formula, to reduce the larger impact constituted to the normal heating performance of air-conditioning;And by the refrigerant for flowing through refrigerant outlet tube road
The mode of heating improves the refrigerant temperature for being back to compressor, to promote heating efficiency, reduces frost condensation to air-conditioning itself
The adverse effect of heating performance.
The embodiment of the present disclosure provides a kind of computer readable storage medium, is stored with computer executable instructions, described
Computer executable instructions are arranged to carry out the above-mentioned control method for air-conditioner defrosting.
The embodiment of the present disclosure provides a kind of computer program product, and the computer program product includes being stored in calculating
Computer program on machine readable storage medium storing program for executing, the computer program include program instruction, when described program instruction is calculated
When machine executes, the computer is made to execute the above-mentioned control method for air-conditioner defrosting.
Above-mentioned computer readable storage medium can be transitory computer readable storage medium, be also possible to non-transient meter
Calculation machine readable storage medium storing program for executing.
The technical solution of the embodiment of the present disclosure can be embodied in the form of software products, which deposits
Storage in one storage medium, including one or more instruction is used so that computer equipment (can be personal computer,
Server or the network equipment etc.) execute embodiment of the present disclosure the method all or part of the steps.And storage above-mentioned is situated between
Matter can be non-transient storage media, comprising: USB flash disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), with
Machine accesses a variety of Jie that can store program code such as memory (RAM, Random Access Memory), magnetic or disk
Matter is also possible to transitory memory medium.
Above description and attached drawing sufficiently illustrate embodiment of the disclosure, to enable those skilled in the art to practice
They.Other embodiments may include structure, logic, it is electrical, process and other change.Embodiment only represents
Possible variation.Unless explicitly requested, otherwise individual components and functionality is optional, and the sequence operated can change.
The part of some embodiments and feature can be included in or replace part and the feature of other embodiments.The embodiment of the present disclosure
Range includes the entire scope of claims and all obtainable equivalents of claims.When for the application
When middle, although term " first ", " second " etc. may be used in this application to describe each element, these elements should not be by
To the limitation of these terms.These terms are only used to differentiate an element with another element.For example, not changing description
Meaning in the case where, first element can be called second element, and same, and second element can be called first element,
As long as " first element " that is occurred unanimously renames and " second element " occurred unanimously renames.First
Element and second element are all elements, but can not be identical element.Moreover, word used herein is only used for describing
Embodiment and it is not used in limitation claim.As used in the description in embodiment and claim, unless context
It clearly illustrates, otherwise "one" (a) of singular, "one" (an) and " described " (the) is intended to equally include plural shape
Formula.Similarly, term "and/or" refers to and associated lists comprising one or more as used in this specification
Any and all possible combination.In addition, when in the application, term " includes " (comprise) and its modification " packet
Include " (comprises) and/or feature, entirety, step, operation, element and/or group including the statement such as (comprising) fingers
The presence of part, but it is not excluded for one or more other features, entirety, step, operation, element, component and/or these point
The presence or addition of group.In the absence of more restrictions, the element limited by sentence "including a ...", it is not excluded that
There is also other identical elements in the process, method or equipment for including the element.Herein, each embodiment emphasis
What is illustrated can be the difference from other embodiments, and the same or similar parts in each embodiment can refer to each other.It is right
For the method disclosed in embodiment, product etc., if it is corresponding with method part disclosed in embodiment, related place
It may refer to the description of method part.
It will be appreciated by those of skill in the art that unit described in conjunction with the examples disclosed in the embodiments of the present disclosure and
Algorithm steps can be realized with the combination of electronic hardware or computer software and electronic hardware.These functions are actually with hard
Part or software mode execute, and can depend on the specific application and design constraint of technical solution.The technical staff
Described function can be realized using distinct methods to each specific application, but this realization is it is not considered that exceed
The range of the embodiment of the present disclosure.The technical staff can be understood that, for convenience and simplicity of description, foregoing description
The specific work process of system, device and unit, can refer to corresponding processes in the foregoing method embodiment, no longer superfluous herein
It states.
In embodiments disclosed herein, disclosed method, product (including but not limited to device, equipment etc.) can be with
It realizes by another way.For example, the apparatus embodiments described above are merely exemplary, for example, the unit
Divide, can be only a kind of logical function partition, there may be another division manner in actual implementation, for example, multiple units or
Component can be combined or can be integrated into another system, or some features can be ignored or not executed.In addition, shown
Or the mutual coupling, direct-coupling or communication connection discussed can be through some interfaces, device or unit it is indirect
Coupling or communication connection can be electrical property, mechanical or other forms.The unit as illustrated by the separation member can be or
Person, which may not be, to be physically separated, and component shown as a unit may or may not be physical unit
With in one place, or may be distributed over multiple network units.Portion therein can be selected according to the actual needs
Point or whole unit realize the present embodiment.In addition, each functional unit in the embodiments of the present disclosure can integrate at one
In processing unit, it is also possible to each unit and physically exists alone, a list can also be integrated in two or more units
In member.
The flow chart and block diagram in the drawings show system, the method and computer program products according to the embodiment of the present disclosure
Architecture, function and operation in the cards.In this regard, each box in flowchart or block diagram can represent one
A part of module, section or code, a part of the module, section or code include it is one or more for realizing
The executable instruction of defined logic function.In some implementations as replacements, function marked in the box can also be with
Occur different from the sequence marked in attached drawing.For example, two continuous boxes can actually be basically executed in parallel, they
Sometimes it can also execute in the opposite order, this can be depended on the functions involved.Flow chart and block diagram institute in the accompanying drawings
In corresponding description, operation corresponding to different boxes or step can also be to be different from sequence hair disclosed in description
Raw, there is no specific sequences between sometimes different operations or step.For example, two continuous operations or step actually may be used
To be basically executed in parallel, they can also be executed in the opposite order sometimes, this can be depended on the functions involved.Block diagram
And/or the combination of each box in flow chart and the box in block diagram and or flow chart, it can the function as defined in executing
Can or the dedicated hardware based system of movement realize, or can come using a combination of dedicated hardware and computer instructions real
It is existing.